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backport-752ec9a9b195.patch
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From 752ec9a9b195759aa7f6059e65155d404654e316 Mon Sep 17 00:00:00 2001
From: Alejandro Vallejo <[email protected]>
Date: Wed, 8 May 2024 13:39:23 +0100
Subject: tools/hvmloader: Wake APs with hypercalls rather than INIT+SIPI+SIPI
... in order to change how LAPIC_ID handling works. Importantly, this allows
us to start APs by vCPU ID in order to query the LAPIC_ID, rather than needing
to know the APIC_ID in order to wake them.
Other improvements avoid:
* The 16bit entry stub
* A LMSW insn, which has no decode assist on AMD and needs emulating fully
* 13 vLAPIC emulations when 3 hypercalls can do
* 4 pages of stack when 1 in plenty
Signed-off-by: Alejandro Vallejo <[email protected]>
Reviewed-by: Andrew Cooper <[email protected]>
diff --git a/tools/firmware/hvmloader/smp.c b/tools/firmware/hvmloader/smp.c
index 082b17f13818..6ebf0b60faab 100644
--- a/tools/firmware/hvmloader/smp.c
+++ b/tools/firmware/hvmloader/smp.c
@@ -22,88 +22,71 @@
#include "util.h"
#include "config.h"
#include "apic_regs.h"
+#include "hypercall.h"
-#define AP_BOOT_EIP 0x1000
-extern char ap_boot_start[], ap_boot_end[];
+#include <xen/asm/x86-defns.h>
+#include <xen/hvm/hvm_vcpu.h>
+
+#include <xen/vcpu.h>
static int ap_callin, ap_cpuid;
-asm (
- " .text \n"
- " .code16 \n"
- "ap_boot_start: .code16 \n"
- " mov %cs,%ax \n"
- " mov %ax,%ds \n"
- " lgdt gdt_desr-ap_boot_start\n"
- " xor %ax, %ax \n"
- " inc %ax \n"
- " lmsw %ax \n"
- " ljmpl $0x08,$1f \n"
- "gdt_desr: \n"
- " .word gdt_end - gdt - 1 \n"
- " .long gdt \n"
- "ap_boot_end: .code32 \n"
- "1: mov $0x10,%eax \n"
- " mov %eax,%ds \n"
- " mov %eax,%es \n"
- " mov %eax,%ss \n"
- " movl $stack_top,%esp \n"
- " movl %esp,%ebp \n"
- " call ap_start \n"
- "1: hlt \n"
- " jmp 1b \n"
- " \n"
- " .align 8 \n"
- "gdt: \n"
- " .quad 0x0000000000000000 \n"
- " .quad 0x00cf9a000000ffff \n" /* 0x08: Flat code segment */
- " .quad 0x00cf92000000ffff \n" /* 0x10: Flat data segment */
- "gdt_end: \n"
- " \n"
- " .bss \n"
- " .align 8 \n"
- "stack: \n"
- " .skip 0x4000 \n"
- "stack_top: \n"
- " .text \n"
- );
-
-void ap_start(void); /* non-static avoids unused-function compiler warning */
-/*static*/ void ap_start(void)
+static void ap_start(void)
{
printf(" - CPU%d ... ", ap_cpuid);
cacheattr_init();
printf("done.\n");
+
+ if ( !ap_cpuid ) /* Used on the BSP too */
+ return;
+
wmb();
ap_callin = 1;
-}
-static void lapic_wait_ready(void)
-{
- while ( lapic_read(APIC_ICR) & APIC_ICR_BUSY )
- cpu_relax();
+ /* After this point, the BSP will shut us down. */
+
+ for ( ;; )
+ asm volatile ( "hlt" );
}
static void boot_cpu(unsigned int cpu)
{
- unsigned int icr2 = SET_APIC_DEST_FIELD(LAPIC_ID(cpu));
+ static uint8_t ap_stack[PAGE_SIZE] __attribute__ ((aligned (16)));
+ static struct vcpu_hvm_context ap;
/* Initialise shared variables. */
ap_cpuid = cpu;
ap_callin = 0;
wmb();
- /* Wake up the secondary processor: INIT-SIPI-SIPI... */
- lapic_wait_ready();
- lapic_write(APIC_ICR2, icr2);
- lapic_write(APIC_ICR, APIC_DM_INIT);
- lapic_wait_ready();
- lapic_write(APIC_ICR2, icr2);
- lapic_write(APIC_ICR, APIC_DM_STARTUP | (AP_BOOT_EIP >> 12));
- lapic_wait_ready();
- lapic_write(APIC_ICR2, icr2);
- lapic_write(APIC_ICR, APIC_DM_STARTUP | (AP_BOOT_EIP >> 12));
- lapic_wait_ready();
+ /* Wake up the secondary processor */
+ ap = (struct vcpu_hvm_context) {
+ .mode = VCPU_HVM_MODE_32B,
+ .cpu_regs.x86_32 = {
+ .eip = (unsigned long)ap_start,
+ .esp = (unsigned long)ap_stack + ARRAY_SIZE(ap_stack),
+
+ /* Protected Mode, no paging. */
+ .cr0 = X86_CR0_PE,
+
+ /* 32bit Flat Mode */
+ .cs_limit = -1U,
+ .ds_limit = -1U,
+ .ss_limit = -1U,
+ .es_limit = -1U,
+ .tr_limit = 0x67,
+ .cs_ar = 0xc9b,
+ .ds_ar = 0xc93,
+ .es_ar = 0xc93,
+ .ss_ar = 0xc93,
+ .tr_ar = 0x8b,
+ },
+ };
+
+ if ( hypercall_vcpu_op(VCPUOP_initialise, cpu, &ap) )
+ BUG();
+ if ( hypercall_vcpu_op(VCPUOP_up, cpu, NULL) )
+ BUG();
/*
* Wait for the secondary processor to complete initialisation.
@@ -113,17 +96,14 @@ static void boot_cpu(unsigned int cpu)
cpu_relax();
/* Take the secondary processor offline. */
- lapic_write(APIC_ICR2, icr2);
- lapic_write(APIC_ICR, APIC_DM_INIT);
- lapic_wait_ready();
+ if ( hypercall_vcpu_op(VCPUOP_down, cpu, NULL) )
+ BUG();
}
void smp_initialise(void)
{
unsigned int i, nr_cpus = hvm_info->nr_vcpus;
- memcpy((void *)AP_BOOT_EIP, ap_boot_start, ap_boot_end - ap_boot_start);
-
printf("Multiprocessor initialisation:\n");
ap_start();
for ( i = 1; i < nr_cpus; i++ )
diff --git a/tools/firmware/hvmloader/util.h b/tools/firmware/hvmloader/util.h
index 8d95eab28a65..1f5ac4ba183e 100644
--- a/tools/firmware/hvmloader/util.h
+++ b/tools/firmware/hvmloader/util.h
@@ -34,6 +34,8 @@ enum {
#undef NULL
#define NULL ((void*)0)
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
void __assert_failed(const char *assertion, const char *file, int line)
__attribute__((noreturn));
#define ASSERT(p) \